Histology is ubiquitous in biomedical research, clinical practice, and the development of diagnostics and therapeutics. Some of the most powerful histological techniques are those that characterize the biochemistry of tissue sections. This characterization is typically achieved by assaying the binding of a molecular probe to a tissue section under a single condition that maximizes specific recognition. We hypothesize that the full power of biochemical tissue analysis is unrealized due to the fact that (a) current assays do not allow systematic variation of the mode of contact between the probe and the tissue section and the force exerted on the bond and (b) only a single type of interaction, a high affinity interaction, between the probe and the tissue section is explored. We will investigate this hypothesis by completing the following specific aims: I. To determine the extent to which the method of contact between the molecular probe and the tissue section influences the results of a biochemical tissue analysis assay. We have developed a technique, termed dynamic biochemical tissue analysis (DBTA), which allows systematic investigation of the interaction of molecular probes with biological tissue samples. In this aim, we will definitively determine if the conditions under which the probing molecule interacts with the tissue (e.g., probes immobilized on microspheres, applied shear force) significantly influences the results of a biochemical tissue analysis. II. To determine if characterization of low affinity probe-tissue section interactions can reproducibly discriminate between cancerous and normal tissue, and between variants of cancerous tissue. Our preliminary studies with DBTA have revealed low affinity interactions between a probing molecule (E-selectin) and cancer tissue sections. Under one set of conditions, these interactions (a) are more numerous on cancerous tissue relative to normal tissue and (b) are statistically different amongst tumor variants. In this aim we will conduct a systematic DBTA to determine if the selectin binding profile for each cancer variant is unique and different from normal tissue. Completion of these aims will give insight into the validity of our hypothesis and will also (a) provide a new approach for analyzing biological tissue and identifying antigens in situ, (b) provide a framework for understanding relationships between the biophysical parameters operative in biochemical tissue analysis, (c) identify conditions under which DBTA can be performed to achieve identification of various tumor types, (d) suggest new ways to classify pathological tissue, and (e) open new avenues for the development of novel diagnostics. The project will provide significant research opportunities for undergraduate and graduate students, thus fulfilling the objectives of the R15 grant mechanism. PUBLIC HEALTH RELEVANCE: The biochemical analysis of tissue is germane to medical research and clinical practice and is used throughout the world to aid the identification, analysis, and prevention of disease. The proposed project seeks to develop a novel approach for analyzing the biochemistry of tissue sections that merges the fields of pathology and cell adhesion. The results of the proposed study will have a significant impact on how tissue samples are analyzed both for research and diagnostic/prognostic purposes.